I installed and configured ZIMBRA on an Ubuntu 16.04 machine. The mails between our company's network (@abc.de) and ZIMBRA (@123.de) works fine. Since we wanted to test ZIMBRA, we dug up an old domain (@123.de) which was used some time ago. To make sure that ALL e-mails with the @123.de domain dont get lost, i created a mail address where all the @123.de mails would be collected.

So I connected to the ZIMBRA host via telnet to test if I can send emails - without success. I include the maillog and the postfix postconf:

I also used the luser_relay option, because all mails with the @123.de domain should be guided towards a static address and the local_recipient_maps =option so that all mails are accepted. Somehow, my relayhostalways gets overwritten after I reboot the VM. I think this is intended and must be kept empty. right?

I modified the main.cf in the /opt/zimbra/common/conf folder since there is the path to ZIMBRA's postfix MTA. After some days of testing, restoring snapshots and shedding many tears, I had the idea to do a clean reinstall of ZIMBRA and leave out the MTA (postfix) when the setup asks which parts of ZIMBRA should be installed. Is it possible to somehow "link" a standalone postfix installation with ZIMBRA? For example, before I do the clean reinstall, I install postfix and after that ZIMBRA itself. Will this work?

with Zimbra you can split the roles through different service but If you need to install an other stand alone Postfix,you should do it on a server without Zimbra. Then after that you can use your Stand alone Postfix as a relay host. To modify the Postfix configuration file when there is no equivalent attribute in the Zimbra LDAP, you should usepostconf -e postfix_attribut='value'and if needs restart the MTA.

what do you mean by "splitting the roles through different services"? Please elaborate My main aim is to avoid the bounced status while trying to catch all incoming mails with the @123.de domain for a static mail address I created in the ZIMBRA admin zone (lets call it dump@123.de). To be more precise: our company has around 100 mail addresses with the @123.de domain. Since we cannot say which one is being used to this day and which not, we want to make sure that if there are still some active ones "floating" around, they won't get lost in the WWW when for example the ZIMBRA test persons write a mail.

For this, I used the luser_relay = dump@123.de option and added the local_recipient_maps = option (left it blank so that nothing is blocked, but all is accepted) in the main.cf so that ALL mails with the @123.de domain will land at dump@123.de. Plus, I have to correct myself. In the current configuration, no relayhost is needed since the VM on which ZIMBRA is installed acts as the host itself.

Unfortunately, the standalone postfix installation on a relayhost is not possible, because when we integrate the testing system to our network for mails being able to be sent to the WWW, we would have a second relay and thus postfix wouldn't know where to get the userdata from (we are using openldap currently). ZIMBRA has its own LDAP which would collide with the second relay if I understand this whole thing right.

TL;DR: Why does my mail get bounced? I'll post an excerpt from the maillog and from a telnet attempt from today:

Nobody with the same problem and/or a solution or hint? This is really driving me crazy and I really dont know what to do.. I even made a clean install of Ubuntu and afterwards a clean ZIMBRA install. Still the same 5.0.0 bounced problem. It is as if something would hinder the very last step before sending out the mail.. and I really would love to know why!

Hey Mark, thanks for your suggestion. I do not want to relay my mail, I just want to catch all incoming ones. To be more specific, I used the operator luser_relay = dump@123.de whichs means that all unknown mails with the @123.de domain which will be received, shall be guided to this specific address. Lets say some1 sends an email to xyz@123.de (which is a not existent address), postfix must be able to catch this one and guide it to dump@123.de. No email with the @123.de domain should get lost which I cant achieve. As it is now, I get an "Undelivered Mail Returned to Sender" (dsn=5.0.0 bounced) notification to my sending address (which is our company's working @abc.de domain).

I tried 3 of the suggestions, but left out the relay one. Still not working, just tested it with telnet.

Okay guys, you wont believe it, but I managed to fix this! FINALLY! Will add the solution just in case anybody will stumble upon the same issue! The whole thing was actually really easy and pretty straight forward to solve. All I had to do (yeah this sounds ridiculous) is to use the following command (as the Zimbra user):

Started to feed google with searches like "zimbra catchall" instead of "zimbra luser_relay etc. and voila, the ZIMBRA Wiki helped me out. Now, when I send a mail to ashadushdaisd@123.de, the mail is still getting bounced (!!!), BUT it still is delivered to my dump@123.de address. This is just awesome! Thank you all for contributing!